The earth's temperature is something I'll probably come back to a few times as it is a lot more involved than you might think. So this is the first part -- the temperature as observed from space.
'Observed from space' shows our first complexity. Satellites can't drop a thermometer into the earth's atmosphere, oceans, etc., to find out what the temperature is. So what can they measure from up there? Fundamentally, they can measure voltages, resistances, currents, counts of an oscillator -- electrical/electronic things like that. Not very helpful at the start. But we can arrange it so that the things we can measure have something to do with what we want to know about.
This is actually how some thermometers work. Think of a traditional old mercury thermometer. It doesn't measure 'temperature', whatever that may be; it measures the length of a thread of mercury. Alcohol thermometers use alcohol instead, but in the same idea. 'Temperature' is the property, then, which makes materials expand (when hotter) or contract (when colder). It was discovered first as a practical matter that materials do expand with temperature in a sense in agreement with our own physical ideas of hot and cold (ex. Mr. Fahrenheit and M. Celsius). So temperature could be equated to expansion of materials. In the 1800s, a firm theoretical basis for which it should be like that (and sometimes not like that at all) was laid down.
For the satellites, a similar process of trying to match up what could be measured to what was desired was involved. The little 'aim it in your ear' thermometers are a little like the satellite method. What they do (satellites more thoroughly, home ear thermometers only in a small color zone) is arrange a detector so that it gets hotter as more radiation falls on it, then measure the resistance/voltage/... of this hotter detector wall.
The satellite detector I've described relies on the Stefan-Boltzmann law to decide temperature -- it measures the energy (which causes the detector to heat up) coming from the earth, and then with the law (Energy = s * T^4, s = the Stefan-Boltzmann constant, wonder why), converts that measured energy to a temperature. That temperature is the 'Black Body' temperature of the earth. If the earth were an ideal black body, the observed amount of energy is what would be seen if the earth were radiating at the given temperature.
We can also make detectors which measure the amount of energy that's within a certain small wavelength interval (blue, for instance). This is how the ear thermometer works, except it uses infrared. Given that observation, and Planck's law (more involved than Stefan-Boltzmann, look it up), we can compute the temperature your inner ear would have to be to be radiating that much energy -- if your inner ear were a black body. It's a fair approximation to one.
In either case, we have a 'Brightness Temperature' -- the temperature the thing you're looking at would have to be to give the observed brightness (energy). In the case of the earth, it is about 255 K, -18 C, 0 F. For Venus it's about 232 K, a good deal colder than the earth. Seriously, check http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html
to verify, or find some others.
What happened? Venus is supposed to be hot! The earth is seldom as cold as -18 C or 0 F anywhere, much less for a planetary average. Well, Venus is hot (over 400 C at the surface) and the earth's surface is rather warmer (about 33 C or 60 F) than the brightness temperature (black-body equivalent temperature -- same thing).
The thing is, we have to pay attention to what the satellites observe -- radiation. If that radiation comes from the surface, we see a surface temperature. But in general, the radiation comes from somewhere up in the atmosphere. For Venus, it is a very long way from the surface, so very much colder. For the earth it is typically several km (or miles) up from the surface.
If you think this is indirect and complicated, wait 'til we talk about trying to observe the temperature of layers within the atmosphere from space!
31 July 2008
30 July 2008
Peer review
"It's peer review, not God review." was my wife's response when I asked her whether she thought peer review meant that a paper was 100% correct in all details. She's right, of course. Humans are fallible, and scientists are human. It seems to surprise nonscientists that we've noticed both of those things. In fact, this is part of why peer-review was invented. Scientists do try to do good, careful, accurate work that is without error. But we know that we probably never accomplish this in our own original writing. Having peer reviewers gives a chance for errors of omission and commission to be caught before you take the paper public (rather, before the journal takes the paper public). Or just plain have some other folks, not as intimately involved in your work as you, look over your explanations for clarity and completeness.
Even after peer review, misteaks can remain. Fallible humans can miss errors even when they're just the reviewers. Again, we know this, too. That's why the significance of peer review is not that it is a stamp of perfection, but a stamp of 'there's a pretty fair chance that this work is worth your time to look at'. Conversely, things which aren't peer reviewed are not even peer reviewed. It doesn't mean that the paper is necessarily bad -- a usenet faq of mine (not formally peer reviewed!) has been cited in the peer reviewed literature (Noerdlinger and Brower) as being the first discoverable time that someone computed how much sea level rise there can be from melting the ice packs. (It isn't zero, see the faq for why and how much. See Noerdlinger and Brower for the more complete considerations and experimental demonstration.) But, given that humans are fallible, and time and reading speed is limited, a mark that there's a better chance than usual that the paper at hand is not obviously (to the reviewers) false is a very helpful thing.
The real test, though, is not whether a paper was peer reviewed. Many papers survive peer review that are never cited by anyone other than perhaps the author. These are dead ends. Since I heard that, I check periodically to see whether my papers get cited. They all have been, and not just by me or someone I was working with at the time. Good to know. The really good papers are the ones which get used often to do new science. Science hangs together, in that if I did my work right, someone else can use it to study, say, polar bears, eider ducks, or something -- things which I had no idea of when I did my work. (I'm not a biological science type, though I find it interesting to hear about.)
The polar bear guy used my work because in the areas he could test it (tracking dead polar bears with transmitters), my work on sea ice drift matched well. He then had confidence that in the areas he couldn't test, the work was probably also worth paying attention to. This is where the good science has happened -- somebody else, for some other reason, can see your work pass an independent test and use it.
Even after peer review, misteaks can remain. Fallible humans can miss errors even when they're just the reviewers. Again, we know this, too. That's why the significance of peer review is not that it is a stamp of perfection, but a stamp of 'there's a pretty fair chance that this work is worth your time to look at'. Conversely, things which aren't peer reviewed are not even peer reviewed. It doesn't mean that the paper is necessarily bad -- a usenet faq of mine (not formally peer reviewed!) has been cited in the peer reviewed literature (Noerdlinger and Brower) as being the first discoverable time that someone computed how much sea level rise there can be from melting the ice packs. (It isn't zero, see the faq for why and how much. See Noerdlinger and Brower for the more complete considerations and experimental demonstration.) But, given that humans are fallible, and time and reading speed is limited, a mark that there's a better chance than usual that the paper at hand is not obviously (to the reviewers) false is a very helpful thing.
The real test, though, is not whether a paper was peer reviewed. Many papers survive peer review that are never cited by anyone other than perhaps the author. These are dead ends. Since I heard that, I check periodically to see whether my papers get cited. They all have been, and not just by me or someone I was working with at the time. Good to know. The really good papers are the ones which get used often to do new science. Science hangs together, in that if I did my work right, someone else can use it to study, say, polar bears, eider ducks, or something -- things which I had no idea of when I did my work. (I'm not a biological science type, though I find it interesting to hear about.)
The polar bear guy used my work because in the areas he could test it (tracking dead polar bears with transmitters), my work on sea ice drift matched well. He then had confidence that in the areas he couldn't test, the work was probably also worth paying attention to. This is where the good science has happened -- somebody else, for some other reason, can see your work pass an independent test and use it.
29 July 2008
Keep your vehicles how you choose
One of the most common responses I get when people learn that I'm a climate scientist is that they tell me we're (climate scientists) all just trying to take away their SUV. Don't know why it's always an SUV when it gets mentioned, but it is. Anyhow, we're not (I don't think so; certainly nobody ever mentioned that policy to me), and I certainly am not. What I'm after is for decisions to be made using good information. Intelligent people of good intent can look at the same information and come to different conclusions. That's life. But a lot of what is out there is bad information. Bad information does not make for good decisions.
For instance, suppose you decided that emitting carbon dioxide was indeed a bad thing to do with the climate system and you have an SUV that gets 20 mpg. Should you toss it for a car that gets 30? I dunno. If you're driving six people in that SUV all the time, and would have to take two cars to carry them instead, you're better off with the SUV. A catch, of course, being that comment about 'all the time'. If very few of your miles are driven with the SUV fully loaded, then two 30 mpg cars would be better. And if the cars were 50 mpg, then even if the SUV really were fully loaded all the time, you would indeed emit less carbon dioxide even with two cars.
One thing I'll add: The people who tell you that climate scientists want to take away your SUV are trying to scare you. They don't want you to think about the science. Even if I'm rather optimistic about some things, I have to figure that people who don't want me to decide based on our best understanding of science are trying to get me to do something I wouldn't if I thought about it.
For instance, suppose you decided that emitting carbon dioxide was indeed a bad thing to do with the climate system and you have an SUV that gets 20 mpg. Should you toss it for a car that gets 30? I dunno. If you're driving six people in that SUV all the time, and would have to take two cars to carry them instead, you're better off with the SUV. A catch, of course, being that comment about 'all the time'. If very few of your miles are driven with the SUV fully loaded, then two 30 mpg cars would be better. And if the cars were 50 mpg, then even if the SUV really were fully loaded all the time, you would indeed emit less carbon dioxide even with two cars.
One thing I'll add: The people who tell you that climate scientists want to take away your SUV are trying to scare you. They don't want you to think about the science. Even if I'm rather optimistic about some things, I have to figure that people who don't want me to decide based on our best understanding of science are trying to get me to do something I wouldn't if I thought about it.
28 July 2008
The Youthful and Damp Dr. Grumbine
A couple of funnies from the last couple days. Yesterday, I was carded in a restaurant when I ordered a beer. Not only am I over 21, but my first paper is as well. :-) Then today I went out to try rowing (scull, not a regular rowboat). Well, the instructor, Cindy Cole http://www.washingtonrowingschool.com/ was good. My wife had been taking lessons for most of the last year (they take the winter off) and, while unsatisfied with how well she was doing (not a teacher issue) was happy about the fact that she had never fallen in to the water. So today I went out to try it, and first time out fell in. This is a rare thing, I'll note. Takes a special level of skill to manage it as only 2 other people have managed it while Cindy's been running the school. I blame the egrets, of which there are many. If you're in the area and have ever wondered about rowing, do come in. I'll be back out Saturday morning, so beware.
Petitioning on climate, part 2
Part 2 here requires a little specialized knowledge, namely that there is a broadly based scientific professional society relevant to climate issues in the US; it is the AGU http://www.agu.org, and they have a class of members who have been recognized for their consistently high quality work (Fellows). The American Meteorological Society, http://www.ametsoc.org, is relevant of course, but is primarily meteorological with only a modest number of oceanographers, glaciologists, hydrologists, ... particularly as compared to the numbers the AGU has. On the other hand, AGU includes space physicists, mineralogists, ... as well, which takes us afield from climate. I'm a member of both societies, so you could call it specialized knowledge to know about them. But these organizations are easy enough to find if you set out looking.
In part 1, we looked a bit at whether the numbers of signers was large. The petition project itself, and even more those who quote it, wants us to believe that there is 'a lot' of scientific opposition. But it turns out that most of the signers are nonscientists, much less scientists in something relevant to climate; worse, the numbers are actually quite small compared to the sizes of the fields they were mass mailing to. Junk mail rate.
For part 2 here, let's look to see whether many of the people in the AGU have signed. We'd want to do a later check whether it was mineralogists vs. atmospheric scientists, but it's a start. Since the AGU has about 50,000 members, I didn't want to try checking the whole list. But AGU fellows are a limited population. Unfortunately, it turns out that the 0.1% I mentioned was how many can be inducted per year. Ouch. There are quite a few more Fellows than I was thinking. Nevertheless, I started checking alphabetically.
Last names beginning with A: 0 of 41 fellows have signed
Last names beginning with B: 0 of 91 fellows have signed
As this is tedious and error prone (just how many 'Browns' are there? yikes. Names like Grumbine are much easier!) I turned to the list of 2008 fellows (not yet included in the full list). There are 51 new members. Checking the names there, I found 2 name matches, but ... Well, the names that matched are Charles R. Bacon and James W. Kirchner. But the Fellow Bacon is working in California and the signer Bacon is in Michigan, while the Fellow Kirchner has a PhD and the signer does not. So we're to 0 of the 51 new Fellows. (I'll note that it isn't a requirement that a Fellow, or AGU member, have a PhD. What matters is doing good work in the area (Fellow) or be studying or have studied the area (member).)
0 of the 183 AGU Fellows I've checked so far have signed the petition. If you'd like to assist the check, please do; send your results to me at plutarchspam at aim dt com. AGU's listing of fellows is at http://www.agu.org/inside/fellows.html The Petition Project's listing of signers is at http://petitionproject.org/gwdatabase/Signers_By_Last_Name.php And, by all means, do recheck my tallies for what I've checked so far.
The real point, though, is that the petition project has tried to mislead us, not the exact numbers. They want us to believe that engineers, doctors, and veterinarians (among other things) are scientists; they're not. They want us to believe that the number of signers is not 'a few', but as I've shown in parts 1 and 2, using only information that requires no special study, it in fact is only a few -- under 1% of the people they consider eligible have signed (in the areas I've checked, to be sure, but I did hit the largest groups). They want us to believe that the petition is about science, but the petition itself doesn't ask any scientific questions (check it out, pay attention to that major weasel word 'catastrophic'), and its main conclusion is actually about signing political agreements -- not science. And ... well, quite a few things, including that being dead is no bar to being on the list. Edward Teller, signer of their sample form, has been dead since 2003.
What should a citizen do when trying to figure out where the science is on climate change? It'd take forever to go through every document on every site and read every book and then apply this sort of method to it. My take is that sources which mislead me on basic things that I can check probably don't suddenly get more accurate in the areas that I can't. If it's a major project of the organization (as opposed to some loose cannon shot off his mouth), then that organization (or that loose cannon) is an unreliable source. This project is a major effort (later spun off to its own project and web domain ) of the http://www.oism.org/, and several of its staff (of 6 faculty and 7 regular volunteers) are the major people involved in the petition project. Your call as to loose cannon vs. institution, but it's several loose cannons from a small group.
That weeds out a couple of web sites and a few people as dubious sources, which doesn't really gain us a lot in a world with millions (billions?) of web sites and billions of web pages.
But we can go another step and consider folks who cite the petition project as showing what the project claimed. As I've shown, it doesn't take much research to find that the project's claims don't match what is really there. So, people and sources that cite it uncritically are at least not doing homework on what they cite to me. I do mention a number of things in chatting with a friend over a beer that I've never researched (life being short already) but that I just heard somewhere. Fine. But it does mean that in those areas I'd be a poor person to try to learn the topic from. Not that I (or those petition-citing sources) are bad folks, but we haven't done homework in those areas. Doing a web search on '31,000 scientists' brings up a ton of hits (something like 40,000). On the first two pages citing the petition uncritically (or even enthusiastically) are:
http://www.worldnetdaily.com/index.php?fa=PAGE.view&pageId=64734
Cites as an 'exclusive', not an editorial. Bob Unruh
http://www.newsbusters.org/blogs/noel-sheppard/2008/05/18/31-000-scientists-rejecting-global-warming-theory-be-named-monday
blog, Noel Sheppard.
http://tadcronn.wordpress.com/2008/05/27/global-warming-consensus-31000-scientists-disagree/
http://www.uncommondescent.com/education/beneficial-natural-warming-31000-scientists/
http://www.canadafreepress.com/index.php/article/3214
Dennis Avery
As best I can see, none are editorials or opinion when at news outlets.
I'll start a summary of unreliable sources, probably at my web site rather than here. Please do suggest other candidates, to the same address. To be a candidate, the site or person must: make an error that can be detected by a nonspecialist -- on an important point to his argument (a primary dubious source), or, cite a primary dubious source uncritically. Not all errors count; for example, in my first paper a word was supposed to be 'parameter', but it got published with 'satellite'. An error, but it didn't affect the argument about ice sheets. For now, it also doesn't count that one person using highly specialized methods detected an error in another highly skilled person's work. I'm going for that citizen level where people can throughly check things out for themselves. That's why, for instance, I have so many links here and the notes are excruciatingly long. Check everything out yourself. If you think I'm wrong, send me your reasons why, with at least equal care to what I've done.
In part 1, we looked a bit at whether the numbers of signers was large. The petition project itself, and even more those who quote it, wants us to believe that there is 'a lot' of scientific opposition. But it turns out that most of the signers are nonscientists, much less scientists in something relevant to climate; worse, the numbers are actually quite small compared to the sizes of the fields they were mass mailing to. Junk mail rate.
For part 2 here, let's look to see whether many of the people in the AGU have signed. We'd want to do a later check whether it was mineralogists vs. atmospheric scientists, but it's a start. Since the AGU has about 50,000 members, I didn't want to try checking the whole list. But AGU fellows are a limited population. Unfortunately, it turns out that the 0.1% I mentioned was how many can be inducted per year. Ouch. There are quite a few more Fellows than I was thinking. Nevertheless, I started checking alphabetically.
Last names beginning with A: 0 of 41 fellows have signed
Last names beginning with B: 0 of 91 fellows have signed
As this is tedious and error prone (just how many 'Browns' are there? yikes. Names like Grumbine are much easier!) I turned to the list of 2008 fellows (not yet included in the full list). There are 51 new members. Checking the names there, I found 2 name matches, but ... Well, the names that matched are Charles R. Bacon and James W. Kirchner. But the Fellow Bacon is working in California and the signer Bacon is in Michigan, while the Fellow Kirchner has a PhD and the signer does not. So we're to 0 of the 51 new Fellows. (I'll note that it isn't a requirement that a Fellow, or AGU member, have a PhD. What matters is doing good work in the area (Fellow) or be studying or have studied the area (member).)
0 of the 183 AGU Fellows I've checked so far have signed the petition. If you'd like to assist the check, please do; send your results to me at plutarchspam at aim dt com. AGU's listing of fellows is at http://www.agu.org/inside/fellows.html The Petition Project's listing of signers is at http://petitionproject.org/gwdatabase/Signers_By_Last_Name.php And, by all means, do recheck my tallies for what I've checked so far.
The real point, though, is that the petition project has tried to mislead us, not the exact numbers. They want us to believe that engineers, doctors, and veterinarians (among other things) are scientists; they're not. They want us to believe that the number of signers is not 'a few', but as I've shown in parts 1 and 2, using only information that requires no special study, it in fact is only a few -- under 1% of the people they consider eligible have signed (in the areas I've checked, to be sure, but I did hit the largest groups). They want us to believe that the petition is about science, but the petition itself doesn't ask any scientific questions (check it out, pay attention to that major weasel word 'catastrophic'), and its main conclusion is actually about signing political agreements -- not science. And ... well, quite a few things, including that being dead is no bar to being on the list. Edward Teller, signer of their sample form, has been dead since 2003.
What should a citizen do when trying to figure out where the science is on climate change? It'd take forever to go through every document on every site and read every book and then apply this sort of method to it. My take is that sources which mislead me on basic things that I can check probably don't suddenly get more accurate in the areas that I can't. If it's a major project of the organization (as opposed to some loose cannon shot off his mouth), then that organization (or that loose cannon) is an unreliable source. This project is a major effort (later spun off to its own project and web domain ) of the http://www.oism.org/, and several of its staff (of 6 faculty and 7 regular volunteers) are the major people involved in the petition project. Your call as to loose cannon vs. institution, but it's several loose cannons from a small group.
That weeds out a couple of web sites and a few people as dubious sources, which doesn't really gain us a lot in a world with millions (billions?) of web sites and billions of web pages.
But we can go another step and consider folks who cite the petition project as showing what the project claimed. As I've shown, it doesn't take much research to find that the project's claims don't match what is really there. So, people and sources that cite it uncritically are at least not doing homework on what they cite to me. I do mention a number of things in chatting with a friend over a beer that I've never researched (life being short already) but that I just heard somewhere. Fine. But it does mean that in those areas I'd be a poor person to try to learn the topic from. Not that I (or those petition-citing sources) are bad folks, but we haven't done homework in those areas. Doing a web search on '31,000 scientists' brings up a ton of hits (something like 40,000). On the first two pages citing the petition uncritically (or even enthusiastically) are:
http://www.worldnetdaily.com/index.php?fa=PAGE.view&pageId=64734
Cites as an 'exclusive', not an editorial. Bob Unruh
http://www.newsbusters.org/blogs/noel-sheppard/2008/05/18/31-000-scientists-rejecting-global-warming-theory-be-named-monday
blog, Noel Sheppard.
http://tadcronn.wordpress.com/2008/05/27/global-warming-consensus-31000-scientists-disagree/
http://www.uncommondescent.com/education/beneficial-natural-warming-31000-scientists/
http://www.canadafreepress.com/index.php/article/3214
Dennis Avery
As best I can see, none are editorials or opinion when at news outlets.
I'll start a summary of unreliable sources, probably at my web site rather than here. Please do suggest other candidates, to the same address. To be a candidate, the site or person must: make an error that can be detected by a nonspecialist -- on an important point to his argument (a primary dubious source), or, cite a primary dubious source uncritically. Not all errors count; for example, in my first paper a word was supposed to be 'parameter', but it got published with 'satellite'. An error, but it didn't affect the argument about ice sheets. For now, it also doesn't count that one person using highly specialized methods detected an error in another highly skilled person's work. I'm going for that citizen level where people can throughly check things out for themselves. That's why, for instance, I have so many links here and the notes are excruciatingly long. Check everything out yourself. If you think I'm wrong, send me your reasons why, with at least equal care to what I've done.
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